In vivo administration of interferon-gamma to patients with rheumatoid arthritis decreases numbers of circulating B cells.

We evaluated the expression of leukocyte cell surface antigens in patients with rheumatoid arthritis (RA) and healthy individuals using monoclonal antibodies and flow cytometry. Both 1 and 2-color analyses were performed. Markers evaluated included markers of T and B cell subsets, activation antigens, and antigens expressed on additional cell types. No major differences were seen between healthy persons and patients. The effects of in vivo administration of interferon-gamma (IFN-gamma) were studied in a clinical trial of the efficacy of this agent in the treatment of RA. Numbers of circulating B cells fell with administration of IFN-gamma. Expression of HLA-DR antigens on monocytes may have increased slightly with IFN therapy. There was no correlation between clinical response to IFN-gamma and change in any immune variables. Because of the observed alterations in B cell numbers, serum immunoglobulins were measured by radial immunodiffusion. There was no alteration of levels of most immunoglobulin isotypes as a result of therapy. There was a modest increase in serum IgA. There was no change in either rheumatoid factor or antinuclear antibody titers during IFN-gamma therapy.